Synthesis And Performance Of Poly(aryl Piperidine) Anion Exchange Membrane

Due to the excessive exploitation and utilization of traditional fossil energy,environmental pollution and energy crisis are becoming more and more serious.The development of clean and efficient new energy has become a research hotspot in countries all over the world.Among them,hydrogen energy,as a clean and renewable energy,has received widespread attention.Fuel cell is a device that uses hydrogen energy to convert chemical energy directly into electric energy through cell reaction.According to the different working media,polyelectrolyte membrane fuel cell can be divided into proton exchange membrane fuel cell(PEMFC)and alkaline membrane fuel cell(AEMFC).At present,the proton exchange membrane fuel cell has been commercialized,but its important component,Nafion membrane,is expensive and requires the use of precious metal Pt as a catalyst,which greatly restricts its use scale and scenarios.In contrast,AEMFC works in an alkaline medium,and the oxygen reduction reaction kinetics is fast,thereby reducing the use of Pt precious metal catalysts and reducing battery costs.In recent years,it has received great attention and research.Anion exchange membranes(AEMs),as the core component of alkaline membrane fuel cells(AEMFC),are mainly composed of a polymer backbone and cations.Among them,polyarylether polymers are often used as the main chain structure of AEMs due to their excellent mechanical properties and thermal stability.However,experiments have found that poly(arylether)polymers are unstable under hot alkaline working conditions,especially when the main chain contains electron-withdrawing groups such as sulfone or ketone groups,the ether oxygen bond is prone to hydrolysis and cleavage,resulting in the degradation of the main chain and shortening the service life of AEMs.Therefore,in order to improve the alkaline stability of AEMs,prolong the service life of AEMs,we designed a polymer backbone without ether oxygen bonds.The poly(biphenyl piperidine)polymer is prepared by the reaction of N-methyl-4-piperidone and biphenyl catalyzed by strong acid.The hydrophilic-hydrophobic comb-shaped AEM was prepared by simultaneously introducing hydrophilic side chains and hydrophobic side chains.The introduction of hydrophobic alkyl chain structure can increase the free volume in the membrane,and the increase of temperature is beneficial to improve the ionic conductivity of the membrane.In addition,after soaking in 80 ℃,1 mol/L Na OH solution for 30 days,the ionic conductivity retention rate of PAP-OH-x membranes is more than82%,showing excellent alkaline stability.In order to further improve the dimensional stability and mechanical properties of AEMs,the cross-linking agent is introduced to obtain a series of cross-linked AEMs.The retention of ionic conductivity of PAP-OH-c-x membranes was more than 85% after being immersed in 1 mol/L Na OH solution at 80 ℃ for 30 days.At 80 ℃,the swelling ratio of the membrane is less than 10%,showing excellent dimensional stability.